Effects of 4 wk of hindlimb suspension on skeletal muscle mitochondrial respiration in rats.
We investigated in rats the effect of 4 wk of hypodynamia on the respiration of mitochondria isolated from four distinct muscles [soleus, extensor digitorum longus, tibial anterior, and gastrocnemius (Gas)] and from subsarcolemmal (SS) and intermyofibrillar (IMF) regions of mixed hindlimb muscles that mainly contained the four cited muscles. With pyruvate plus malate as respiratory substrate, 4 wk of hindlimb suspension produced an 18% decrease in state 3 respiration for IMF mitochondria compared with those in the control group (P < 0.05). The SS mitochondria state 3 were not significantly changed. Concerning the four single muscles, the mitochondrial respiration was significantly decreased in the Gas muscle, which showed a 59% decrease in state 3 with pyruvate + malate (P < 0.05). The other muscles presented no significant decrease in respiratory rate in comparison with the control group. With succinate + rotenone, there was no significant difference in the respiratory rate compared with the respective control group, whatever the mitochondrial origin (SS, or IMF, or from single muscle). We conclude that 4 wk of hindlimb suspension alters the respiration of IMF mitochondria in hindlimb skeletal muscles and seems to act negatively on complex I of the electron-transport chain or prior sites. The muscle mitochondria most affected are those isolated from the Gas muscle.
Yajid
F
F
Laboratoire de Physiologie des Interactions, Hôpital Arnaud de Villeneuve, Montpellier, France. physio.montp@hol.fr
Mercier
J G
JG
Mercier
B M
BM
Dubouchaud
H
H
Préfaut
C
C
D000818:Animals; D001835:Body Weight / Q000502:physiology; D019069:Cell Respiration; D002950:Citrate (si)-Synthase / Q000378:metabolism; D019417:Hindlimb Suspension / Q000009:adverse effects*; D008297:Male; D008931:Mitochondria, Muscle / Q000201:enzymology / Q000378:metabolism*; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism / Q000648:ultrastructure; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D009210:Myofibrils / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012508:Sarcolemma / Q000378:metabolism
D011506:Proteins; D002950:Citrate (si)-Synthase